1. Technical Field
The present invention relates to an electrophoretic display device, an electronic timepiece, and an operating method of an electrophoretic display device.
2. Related Art
Display panels known as electrophoretic display (EPD) panels capable of continuing to display an image even when the power is turned off have been developed, and practical electrophoretic display devices using such EPD panels are widely available. Because an EPD panel can retain the displayed image for a certain period of time even when power is not supplied, enabling low power consumption operation, and EPD panels can also provide a 180-degree viewing angle, wristwatches using electrophoretic display devices (called EPD watches below) have also been developed. Technology related to EPD watches is disclosed in JP-A-2009-103967, for example.
An example of a function block diagram of an EPD watch according to the related art is shown in FIG. 14. As shown in FIG. 14, an EPD watch according to the related art has a customized microcontroller (MCU) specifically designed as a processor for an EPD watch to achieve low power consumption, and the MCU includes the function of a real-time clock (RTC) using a crystal oscillator as the master clock and controls displaying the time on the EPD panel.
However, because the program controlling operation of a conventional EPD watch is rendered by a mask ROM (read-only memory) and must be fixed when the MCU is manufactured, assuring sufficient time for program development may be difficult. In addition, if the specifications change after the program is fixed, the MCU must be redesigned, and shortening the development time and reducing cost are also difficult. Using a more versatile MCU that does not rely on a mask ROM as the processor of the EPD watch is therefore desirable, but optimizing the process of an existing general purpose MCU having an RTC function is difficult, and increased power consumption when compared with using a custom MCU is unavoidable.